Fix the problem in parseOctal and throw exception if use \xhh to specify hex value (#23198)
Summary:
follow the rules:
1) https://docs.python.org/2.0/ref/strings.html
2) https://en.cppreference.com/w/cpp/language/escape
didn't find anything about the format \h
Pull Request resolved: https://github.com/pytorch/pytorch/pull/23198
ghstack-source-id: 86986691
Reviewed By: zrphercule
Differential Revision: D16431215
fbshipit-source-id: 7b342708d1984e08b3cbbcf6d487623f1dc63a14
